Ovarian cancer is among the most lethal gynecologic malignancies in developed countries. In the United States, approximately 23,000 women are diagnosed with the disease and almost 14,000 women die from it each year. There are three main types of ovarian cancer: epithelial, germ cell, and sex cord stromal. About 90% of ovarian cancers start in the epithelium tissue, which is the lining on the outside of the ovary. This type of ovarian cancer is divided into serous, mucinous, endometrioid, clear cell, transitional and undifferentiated types. The risk of epithelial ovarian cancer increases with age, especially after the age of 50. Germ cell tumors account for about 5% of ovarian cancers. They begin in the egg-producing cells. This type of ovarian cancer can occur in women of any age, but about 80% are found in women under the age of 30. The main subtypes are teratoma, dysgerminoma, endodermal sinus tumor and choriocarcinoma. Sex cord stromal tumors, about 5% of ovarian cancers, grow in the connective tissue that holds the ovary together and makes estrogen and progesterone. Most are found in older women. Despite progress in cancer therapy, ovarian cancer mortality has remained virtually unchanged over the past two decades. Given the steep survival gradient relative to the stage at which the disease is diagnosed, early detection remains the most important factor in improving long-term survival of ovarian cancer patients.
Endometrial cancer is the most common gynecologic malignancy and accounts for about 13% of all malignancies occurring in women. There are about 34,000 cases of endometrial cancer diagnosed in the United States each year. All endometrial carcinomas arise from the glands of the lining of the uterus. Adenocarcinoma accounts for 75% of all endometrial carcinoma. Endometrial adenocarcinomas that contain benign or malignant squamous cells are known as adenocanthomas and adenosquamous carcinomas respectively and account for 30% of endometrial cancers. The remaining types of endometrial carcinoma have a poorer prognosis. About 3% have a clear cell carcinoma, and about 1% have a papillary carcinoma.
Currently, there are no convincing early detection approaches for endometrial and ovarian cancers. Although it is well established that some endometrial and ovarian tumors shed cytologically recognizable cells in routinely prepared Pap tests, it is clear that this approach rarely detects occult tumors. Accordingly, efforts to develop means of collecting biological samples that have high patient acceptability, good sensitivity for detecting early disease, and excellent specificity are needed.